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<< The Transit: A Simple Explanation >> |
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The word 'Transit' means movement or 'in passage'. Venus, as we know, is an inner planet. Almost every century, Venus catches up with Earth and actually passes it. When this happens, we can see the planet move from left to right across the lower half of the sun.
This rare phenomenon is called a Transit, and we are very lucky to be able to witness it this year in 2004, as well as in 2012. Officially, the transit begins on June 4, 2008 at 05:13 Universal Time. http://aa.usno.navy.mil/data/docs/Venus2004.pdf, is a site that lists local time for many major cities around the world, from where the Transit of 2004 can be observed.
The Transit of Venus occurs in a strange, reoccurring pattern: once in every 122 years, then after 8 years and then the next will arrive after 105 years. Below is a list of the documented transits in our history:
These rare occasions have had a huge impact on science (especially astronomy), human culture and global interactions.
The main problem that astronomers faced hundreds of years ago was the fact that they did not have an accurate scale with which to measure outer space. Scientists had determined the size of the solar system by striking ratios between various parts of the solar system, but did not have a grasp of the actual size of whatever they were observing. One of the key things that their ratio-calculations were based upon, was the distance between the Earth and the Sun. This distance was known as the Astronomical Unit (AU), yet no one knew the exact size of the AU. Says the education director of the New Zealand Stardome Observatory, Kate McKinney: “It was like someone telling you that the dairy was 2 km down the road, but you had no idea how big 2 km was…”
The AU had to be extremely precise and accurate, because a minute error would be magnified millions of times, as the AU was used as a scale for measuring the entire universe.
The Transit of Venus was important to astronomy because it gave scientists a way of calculating the value of the Astronomical Unit. Every century, beginning with the first documented observation in 1631 by Jeremiah Horrocks, scientists prepared meticulously for the phenomenon that, if exploited to its fullest potential, would give astronomy a solid base.
Details about each historical observation and their respective impacts will be given on future pages.
So began the quest for determining the exact value of the Astronomical Unit, and indirectly, scientists walked the path that would allow them to find the place of humans in the scheme of ‘bigger things’. It was a quest, riddled with many difficulties and dangers, which eventually affected the whole world: culturally and scientifically.
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